The Department of Homeland Security (DHS) has administered the nation's immigration laws since March 1, 2003 when the Immigration and Naturalization Service became part of DHS. Through the U.S. Citizenship and Immigration Services (USCIS), DHS continues the tradition of welcoming immigrants into the country by administering services such as immigrant and nonimmigrant sponsorship; adjustment of status; work authorization and other permits; naturalization of qualified applicants for U.S. citizenship; and asylum or refugee processing. Immigration enforcement, which is the responsibility of the Directorate of Border and Transportation Security, includes preventing aliens from entering the country unlawfully, detecting and removing those who are living in the U.S. unlawfully, and preventing terrorists and other criminal aliens from entering or residing in the United States. The Department makes certain that America continues to welcome visitors and those who seek opportunity within our shores while excluding terrorists and their supporters.